Mixing apparatus



April 16, 1940. M. A. DIBBLE Er AL 2,196,983

MIXING APPARATUS Filed Jan. 3, 1939 Mar'iEn-L A. Dibble Eiclr dun H.M'-E,ur*mi|:.k Raul: E1.Russel Patented Apr. 15,1946

UNITED S'lATES PATENT OFFICE 2,196,983 mxmc. APPARATUS" v wareApplication January 3, 1939, Serial No. 2 i9,1l6

3 Claims.

This invention relates to mixing machines and more particularly toapparatus for handling hea y and viscous mixtures.

In the mixing of materials in a highly viscous state, and particularlyin 'pigment dispersion where high cohesive force is desired to bringabout the desired shearing action on the pigment particles, varioustypes of mixing machines have been proposed to develop the large forcesrequired. The mixing means suggested has included the extrusion of theplastic material under high compression through a perforated plate, theuse of mixers provided with a single worm, and two blade dispersionmixers. The apparatus available, however, has been unsatisfactory fromone or more of the standpoints of convenience of operation, amount ofmaterial handled in a given time, and development of the high extrusiveforces necessary for eiiicient dispersing or tics or pastes, with rapidand complete mixing or dispersion of the ingredients of the mass. Otherobjects will appear hereinafter.

The preferred embodiment of our invention is illustrated by theaccompanying drawing in which Fig. I an isometric view with parts brokenaway showing the-dispersion or mixing apparatus with its arrangement ofdouble worms used in the practice of this invention; v

Fig. 2 is a view of the scraper end of the worms; Fig. 3 is a side viewof one of the duplicate worms; and V .Fig. 4 is a view worms. v

- The closely adjacent pairs of worms l and 2 of the same pitch and withthe thread running in the same direction are rotatably mounted withtheir axis parallel in the vessel or tank 3 mounted of the extrusion endof the on a suitable support orfframe structure which includes thehorizontal member 4 and a vertical member 5.. The bottom of the vesselis formed into two troughs extending under and along the worms as shown.

The 'wornzs are rotated in opposite directions by a motor I which bymeans of shaft 8 and clutch 8 drives suitable reduction gearing in thehousing Ill from which the sprocket. II is driven. The chain 12 connectsthe sprocket II with the larger sprocket l3 rigid with one of the wormshafts I which are in turn rigid with the worms. other worm is driven atthe same speed in the The opposite direction. by means of spur gears notshown which connect the two Shafts. The worm shafts are rotatablymounted in conventional manner in the end plates 20 and 2|, whichtogether with the side frames carry the total power load.

The ends of each worm are somewhat differently formed, the end indicatedby the numeral l5 being the scraper end and the end indicated by thenumeral It being the extrusion end. The pitch of each worm becomes zeroat the extrusion end only on which is formed the extrusion or dispersionblades I1 and t8, the planes of which are atright angles to the wormaxis. The outer end of one blade, ll, is the termination of the wormspiral which recedes back of the plane of the blades so that the outerend of the opposite blade I8 is spaced one-half the pitch of the wormfrom the adjacent spiral. This last 'mentioned blade although desirableis not essential. The scraper end it, however, has a relatively sharpedge It as would be formedby cutting through the worm at right angles tothe axis.

In the construction shown in the drawing the portion of the spiral wherethe pitch is zero, a width of one to a few inches from the edge of thespiral perpendicular to the worm axis, is machined to a flat face toform the dispersion blade H. The supplemental blade l3, cast integralwith the hub of the worm, is of zero pitch for at least a portion of itswidth, this portion being formed with a face similar to that on bladell. These faces are in the same plane and are parallel but may be offsetin the sense that the plane of one blade is not necessarily an extensionof the other through the hub. The blade l8 may be wider than thedispersion face formed therein and extend beyond it in the direction ofrotation and this additional width formed into a portion which followsthe pitch of the worm.

The worms are constructed to avoid the con-' siderable difllculty incleaning them that would otherwise be experienced through the provisionof self-cleaning fillets in the form of the built-up concave portions 24extending between the worm blades or spirals.

During the mixing, vehicle may be added when treated. For a thirtygallon mixer'the diameter and length of the worms is preferably about 15inches, the pitch 9 inches, revolutions per minute 6 and .the width ofthe dimension of the tank 5 at right angles to the worm axis about 30inches.

These figures may of course vary somewhat, as for instance the wormlength may be thirty inches, the pitch from 6 to 12 inches, and therevolutions per minute from 25 to 90.

In operation, a portion of the mass conveyed by the worm 2 to theextrusion end I8 is squeezed with a wiping action'under great forceagainst the end plates 2| or other abutment member spaced slightly,usually about '3 inch, from the end of the worm. This clearance distancemay be varied by spacer strips inserted between the flanges 23 and theend plates, or by means of at the scraper end of that wormwhich conveysthe mass to the oppositeor extrusion end of worm i where a portion ofthe mass is again squeezed, against the end plate and transferred tothescraper end of worm 2. This circuit of action, in which portions of themass are continuously squeezed under great force and incorporated intothe body of the material beingv treated,is thus continuously repeated. p

Although the present invention asipreviously indicated is particularlyuseful for pigment dispersion, it is applicable to any type of mixing,'r'e-' l 'quiring handling of very heavy and viscous pastes in a singleworm mixer this cycle is in a vertical where extrusion is an essentialor desirable part of the mixing operation. The mechanismdescribed hereinmay for instance be used as'a putty chaser, a soap crutcher, doughmixer, and for mim'ng plastic and abrasive'compounds.

The mechanism described herein presentssev eral important advantagesover the types' of mix-1 ers heretofore used for similar-purposes; .The

present invention is characterized by extrusion under great pressure, atype of action notinolved in the two blade dispersion mixers whichdepend on a shearing or pulling, apart action. In comparison with singleworm mixers it observed that the extrusion action at one emi" oi thepresent mechanism and a cleaning'or scraping action at the o 'osite endare features pp 1 the scraper end of the companion worm, and an abutmentplate spaced a short distance from-the which cannot be prwent in singleworm mixers greases terial in the present mixer constantly beingsubjected to an extrusion force by .one worm or "is being returned tothe opposite end of the parallel worm for similar extrusion. Thearrangement. of

the worms in the mixer leaves, to all practical purposes, no dead spotor no spot where thematerial does notmove in any direction-but liessomewhat dormant. A fin'ther' advantage resides in the mixing ordispersing in the center" of the mixer due to the opposite relativerotation of the worms and in the factthat the direction'ofrotationistowards the adjacent worm and this keeps thesides of the mixer free froma pile-up or material on thesides. It is for this reason that thewormsare preferably 01. similar threads and rotated in the samedirection The threads,

however, may be opposite and rotation of the worms in the same directionsince. many or the other advantages are retained; The larges'elifcleaning fillets in the worms results iii more readily obtainingthe desired state-of homo-f geneity. The, present mixer. may be emptiedThe present construction readilyallows readily through valve openings atthe endof'the' mixer and does not need to be'raised, asTIn-the dumpingmethod; applied to known existing equipment, as for instances. Wernerifleiderer mixer.

for adjustable end clearance fifthe worms from the' end plates whichmakes possible-a variable 0 degree of dispersion, The supplementaryextru 'sion blade adds further to-the advantage of our new apparatussince the extra blade contributes] to more efllcien'tdispersion due tothe increased extr'udin'g area.-

As many apparently "widely; difierent embodiments of this invention 'maybe made withoutdeparting from the spirit and scope thereof, it-is 'to beunderstoodthat we do not limit ourselves:

except as 1 to the specific embodiments thereor defined in the appendedclaims.

We claima. 1. Inia-mixing rial being toward opposite ends of the" worms,one end, of worm terminating in a apparatus substantially paralleladjacentcompanion worms, meansior rotating portion ofzero-'pitclioniwhich portion an extra-ruse of the fundamental diflerencein de-.- I

plane, whereas in our mixer thisv cycle of rotation is in ahorizontalplane which results in muchiaster arrival'at on ogeneity,Themas on face'is formed, thepitch of the worm .contlnuinglthroughto'ascrapes end at the opposite end of the worm, said worms being positionedwith the extrusion iaceoi one worm adjacent to ends or; theIwormsagainst which thematei'ial. being mixed-is extruded and wiped by,said extrusion'd'ace to said scraper end.

2. The-"mixing a'pparatusset forth in claim v 1 rotatable inoppoflte'directions,"

' V -MARION".A. DIBBLEL i in which the worms are'of thesam'e thread andnoanon R. McCORMICK- aussmin

